class IPersistentDataStructure
{

    public:
        virtual ~IPersistentDataStructure();

        virtual IPersistentDataStructure &SetVersion(size_t) = 0;
        virtual size_t GetVersionCount() const = 0;
        virtual size_t GetCurrentVersion() const = 0;

};

class CAbstractPersistentDataStructure:
    public IPersistentDataStructure
{

    public:
        CAbstractPersistentDataStructure();
        CAbstractPersistentDataStructure(const CAbstractPersistentDataStructure &);

        CAbstractPersistentDataStructure &operator=(const CAbstractPersistentDataStructure &);

        // ...

};

template<typename T, typename Operation>
class ISegmentTree
{

    public:
        virtual ~ISegmentTree();

        virtual ISegmentTree<T, Operation> &Change(size_t, const T &) = 0;
        virtual T operator()(size_t, size_t) const = 0;

};

template<typename T, typename Operation, T DefaultValue>
class CSegmentTree:
    public ISegmentTree<T, Operation>
{

    public:
        template<typename InputIterator>
        CSegmentTree(InputIterator, InputIterator);
        CSegmentTree(const CSegmentTree<T, Operation, DefaultValue> &);

        // ...

};

template<typename T, typename Operation, T DefaultValue>
class CPersistentSegmentTree:
    public CAbstractPersistentDataStructure, public ISegmentTree<T, Operation>
{

    public:
        template<typename InputIterator>
        CPersistentSegmentTree(InputIterator, InputIterator);
        CPersistentSegmentTree(const CPersistentSegmentTree<T, Operation, DefaultValue> &);

        // ...

};